Wounding and Altered Cell Cycles

Epithelial tissue is normally quiescent, stationary, and non-invasive, but following wounding this tissue dramatically changes its behaviors becoming proliferative, migratory, and invasive. In addition to proliferation, wounds induce other cell cycle behaviors such as G2 stalling and increased DNA content within single cells. However, the mechanisms by which these behaviors are induced and patterned are not known. To explore these questions, we induce laser wounds in the pupal notum, an epithelial monolayer that can be live-imaged throughout the repair process. Preliminary data from our lab using a cell cycle indicator fly (FUCCI) indicates that cells stall in the G2 stage of the cell cycle around wounds. This G2 stalling behavior has been previously reported to be JNK-dependent in imaginal wing discs wounded ex vivo. Our FUCCI data also reveals an apparent increase in nuclear volume close to the wound margin suggesting DNA content increases in this tissue. It has been reported that Yorkie, the fly homologue to Yap/Taz, and its downstream effectors drive increased DNA content through endocycling (re-replication without division) in response to wounds in adult epithelium. To investigate DNA content increases in the Drosophila pupa we developed a novel dissection and fixation protocol allowing us access to this previously unstainable tissue. By combining in vivo live-imaging with our dissection and staining protocol of the pupal notum we aim to understand the wound-induced signals that pattern these cell cycle behaviors in the tissue surrounding a wound.